It is commonly seen that many computers and peripheral apparatuses, such as scanners, digital cameras, removable hard disks, etc, introduce the Universal Serial Bus (USB) specification into the connection interface of a transmission connector. The USB connector can unify various specifications for various connectors so as to overcome the conventional shortcoming of providing a specific connector for a specific apparatus.
A computer is generally equipped with two USB female sockets. Moreover, the existing peripheral apparatus of the computer is mainly equipped with the USB male plug. In response to this, the new generation computer is always equipped with several USB female sockets for insertion of the USB male plugs on the peripheral apparatuses.
Nevertheless, for the purpose of not changing the dimension of the computer or reducing the occupied space of the computer, such as the barebone system, the positions and depths of the USB female sockets formed in various computers are different from one another. Accordingly, the following problems are caused, in which:                1. If the USB female sockets are mounted excessively deep, the USB male plug cannot be inserted into the USB female socket even through they are provided complying with the specification.        2. If the number of the USB female socket is increased, a USB male plug cannot be inserted into a USB female socket when another excessively close female socket is occupied by another USB male plug.        
In view of the shortcoming in the conventional structure, an extendable USB male plug for overcoming excessively deep position and insufficient space problems of the USB female socket is provided in accordance with the motive of the present invention.